1 Berlin School of Mind and Brain & Department of Psychology, Humboldt-Universität zu Berlin, Berlin, Germany. maria.woitow@hu-berlin.de.
2 Department of Psychiatry and Biobehavioral Sciences, Jane and Terry Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA, USA.
3 Department of Psychology, University of Greifswald, Greifswald, Germany.
4 Department of Psychology, Concordia University, Montreal, QC, Canada.
5 Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI, USA.
6 Department of Neuroscience, Brown University, Providence, RI, USA.
7 Berlin School of Mind and Brain & Department of Psychology, Humboldt-Universität zu Berlin, Berlin, Germany.
8 Science of Intelligence, Research Cluster of Excellence, Berlin, Germany.
9 Department of Experimental Psychology, Ghent University, Ghent, Belgium.

Humans learn not only from their own experiences but also by observing others. Prior research has shown that reward prediction errors (RPEs) - the difference between expected and received outcomes - guide both experiential and observational reinforcement learning. While RPEs from direct experience have been linked to memory formation, it remains unclear whether vicarious RPEs play a similar role in observational learning. Using an incidental memory paradigm, we investigated how experiential and observational learning in a decision-making task shape memory and examined the role of RPEs in this process. Although recognition accuracy did not differ between learning conditions, participants reported higher confidence in memories from experiential trials. Notably, across both learning conditions, gambling and positive RPEs during memory item presentation were associated with enhanced memory. These findings advance our understanding of how observing others' choices and outcomes affects episodic memory by emphasizing shared encoding mechanisms with experiential learning.